They do different things. Protein is required to build muscle, whereas Creatine supplements supposedly replace the muscles own Creatine, which is lost during intense exercise, therefore, the muscles cannot continue to work hard. By replacing depleted Creatine, it means the muscles can work harder for longer.
Both Protein or Whey supplements and Creatine can be purchased from any health shop or online stores like LA Muscle or Maximuscle.
The body can only process a certain amount of Protein, so you need to work out how much is required by height to weight ratio, too much Protein can cause bad, smelly wind. Too much Creatine has been known to cause damage to the Liver and Kidneys.